The picture of Golden Tiara look exactly as the ones i got in a bag of 10 mixed hostas last spring.3 of them was undulatas and planted in my garden, the rest was unknown and planted in pots on the patio. First they looked very nice 2 colored, but after some time they got the same brown spots as in your pic, and they spread. It was the time I first read abouth hosta virus X, and after a few weeks they hit the trash. The undulatas are still fine, even they have been cramed in a bag.
Holland is the biggest plant exporter in the world. What about contacting lots of other respectable nurseries, hosta library, the hosta societies and make a common front against them. Hit them on their money, think it is the only thing they understand. It is not a new problem no more, and they have no excuses.
This in conectionwith the inspectors will hit the bad ones - I hope
Thanks for the update